As a method for performing compression molding to a molten material, such as a resin in a mold, an injection compression molding method for injecting a molten material into a closed cavity from an injection machine and then compressing the molten material is well known. However, the injection compression molding method has problems since the fiber material may be damaged due to high pressure applied to the molten material during the injection or the fiber material may not be easily charged during injection if the molten material has bad fluidity. In addition, a compression molding method for supplying a molten material to a cavity surface of a lower mold in a state where a mold is open, then closing the upper mold and the lower mold, and compressing the molten material is also known in the art. The compression molding is classified into a compression molding called a transfer molding in which a molten material relatively maintaining its origin form is supplied from a port into a mold, and a compression molding called a stamping mold in which a molten material in a fluid state is supplied from an injection machine or an extrusion machine into a mold.
In case of the stamping molding, since the resin supplied to the lower mold is in a fluid state, it is preferable that a movable mold is moved with high precision and pressurized. Patent Literature 1 is known to conform to the above. Patent Literature 1 discloses that a mold may be moved with high precision by means of position control with respect to a resin material supplied by a material supply device. However, in Patent Literature 1, depending on a shape of the molded product or a supply position of a corresponding resin, the degree of parallelization of a movable mold with respect to the fixed mold may not be maintained. In other words, in the stamping molding, the resin material is not initially pressurized at the center of the mold, and if pressurization is initiated at a location other than the center, the degree of parallelization may not be maintained between the fixed mold and the movable mold. In addition, if the degree of parallelization of the movable mold with respect to the fixed mold is collapsed at an early pressurization stage, it may be difficult to manufacture a final molded product to have a desired plate thickness. Moreover, this problem worsens if a material with bad fluidity such as a large-sized molded product or a resin including carbon fiber is used.
As a solution to the above problem, Patent Literature 2 is known in the art. Patent Literature 2 discloses that the degree of parallelization between a movable mold with respect to a fixed mold is maintained by means of an equilibrating device installed to appear on a bed. In Patent Literature 2, the equilibrating device is installed separately from a pressurizing cylinder with a long stroke. In addition, Patent Literature 2 does not disclose how the position control is performed during the compression molding by using the equilibrating device and how the press pressure control is performed during the stamping molding. Moreover, Patent Literature 2 does not disclose how the position control or the like is performed when the mold is open. Further, Patent Literature 2 discloses a plastic material as the material to be molded, and it is unclear which material is used for molding.